Effects of polyaluminum chloride and lanthanum-modified bentonite on the growth rates of three Cylindrospermopsis raciborskii strains

PLoS One. 2018 Apr 3;13(4):e0195359. doi: 10.1371/journal.pone.0195359. eCollection 2018.

Abstract

In tropical and subtropical lakes, eutrophication often leads to nuisance blooms of Cylindrospermopsis raciborskii. In laboratory experiments, we tested the combined effects of flocculant polyaluminum chloride (PAC) and lanthanum-modified bentonite (LMB) on the sinking and growth rates of three C. raciborskii strains. We tested the hypothesis that the combination of PAC and LMB would (1) effectively sink C. raciborskii in a test tube experiment and (2) impair C. raciborskii growth, irrespective of the biomass of the inoculum (bloom) and the strain in the growth experiment. We tested the recommended (LMB1) and a three-times higher dose of LMB (LMB3). The combined addition of PAC and LMB enhanced the sedimentation of all C. raciborskii strains. Moreover, both the PAC and LMB doses decreased the phosphate concentration. PAC and LMB1 decreased the growth rate of all strains, but the efficacy depended on the biomass and strain. The combined addition of PAC and LMB3 inhibited the growth of all strains independently of the biomass and strain. We conclude that a low dose of PAC in combination with the recommended dose of LMB decreases C. raciborskii blooms and that the efficiency of the technique depends on the biomass of the bloom. A higher dose of LMB is needed to obtain a more efficient control of C. raciborskii blooms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Hydroxide*
  • Bentonite* / chemistry
  • Biomass
  • Chlorophyll / metabolism
  • Chlorophyll A
  • Cylindrospermopsis / growth & development*
  • Cylindrospermopsis / metabolism
  • Lanthanum* / chemistry
  • Phosphorus / metabolism

Substances

  • Bentonite
  • aluminum oxychloride
  • Chlorophyll
  • Phosphorus
  • Aluminum Hydroxide
  • Lanthanum
  • Chlorophyll A

Grants and funding

The authors thank W. Beekman-Lukassen for her assistance during the lab work. F.A. was supported by a Sandwich Ph.D. fellowship from CAPES (Foundation for the Coordination of Higher Education and Graduate Training, Brazil—BEX 5135/11-7). This study was conducted under the flag of the CAPES (Brazil)/Wageningen University (The Netherlands): CAPES-WUR project 004/2008. Preparation of the manuscript was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Process Number: Universal 407783/2016-4. The funders had no role in study design, data colletion and analysis, decision to publish, or preparation of the manuscript.